Ionic liquids are materials which melt at low temperatures, i.e. at or below ambient working conditions but are ionic salts. Recently they have received much attention for applications in green chemistry, replacing commonly used organic solvents in many kinds of reactions or in bi-phase catalysis. Whereas all of the previously known ionic liquids have been non-energetic materials, the materials of this invention have strongly oxidizing anions which are paired with either the well known alkyl substituted imidazolium or pyridinium cations or more energetic cations carrying either energetic or oxidizing substituents, such as azido- or nitro- groups. These cations serve as the fuel, resulting in highly energetic materials having applications in propulsion and explosive technologies.
One of the major hurdles to overcome in designing and making new propellants is creating an oxygen balance of fuel to oxidizer in one system. There is a large array of materials that are fuels, but relatively very few materials carry excess amounts of oxygen atoms to support the combustion of added fuels. Prior workers in the field have been investigating mixtures of oxygen rich salts of hydroxylammonium nitrate (HAN) with a wide array of fuel compounds as monopropellant materials.
Examples of related patents are U.S. Pat. No. 5,223,057 to Boggs et al. (1991), U.S. Pat. No. 6,001,197 to Wagaman (1999) and U.S. Pat. No. 6,331, 220 to Wagaman (2001). In spite of all these new materials, none of them offer the advantages of the compounds of the present invention, i.e., homogenous, highly energetic, single-phase systems exhibiting no vapor pressure over a very wide temperature range, thereby avoiding vapor toxicity and handling problems. Many of the previously described, highly reactive materials such as amine-, hydroxylammonium-, hydrazine-, or azido-based compounds, can be difficult to handle and/or be highly toxic and/or explosive. All of these materials are formulations, i.e. are mixtures with other energetic materials which often requires the use of stabilizers, solvents and chelating agents to make the formulations reasonably stable/usable. This is highly undesirable from a practical point of view, as mixtures can degrade, separate, or precipitate ingredients over time or during thermal cycling.
Thus, there is a need and market for energetic materials that overcome the above shortcomings.
There have now been developed novel energetic materials of low vapor pressure and reduced toxicity as described below.